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Ammonia is one of the deleterious water quality parameters that must be managed for successful aquaculture production. The present study evaluated the impact of chronic ammonia exposure on the physio-biochemical and immunological responses of Etroplus suratensis. Fish (n = 120, 24 ± 3 g) were exposed to four different ammonia concentrations (0, 1, 2, and 4 mg L−1 of Total ammonia nitrogen (TAN)) at 27.5 to 29.70C for 30 days. The unionized ammonia concentrations are 0, 0.014, 0.028, 0.057 mg L−1. The lowest haemoglobin (Hb) level was observed in fish exposed to the highest level of TAN (4 mg L−1). The serum glucose, cortisol, liver superoxidase dismutase, catalase activities, enzymes such as alkaline phosphatase, Serum Glutamic- Oxaloacetic Transaminase, and Serum Glutamic- Pyruvic Transaminase were higher in fish exposed to 4 mg L−1 TAN than the control group. The serum total protein and albumin levels were substantially decreased with TAN exposure. Immune parameters such as Immunoglobulin M and Tumour Necrosis Factor—alpha were significantly (P < 0.05) lower in the groups exposed higher ammonia concentrations than the unexposed group. The heat shock protein 70 gene expression was significantly higher at 1 mg L−1 TAN, and the Insulin-like growth factor-1 gene expression was lower (P < 0.05) at 4 mg L−1 TAN. This is the first detailed investigation on the impact of chronic ammonia exposure in the culture fish E. suratensis. This study reveals that a chronic exposure to TAN even at lower concentrations, such as 1 mg L−1 TAN in fresh water can have a negative impact on E. suratensis physico-biochemical and immunological responses. Hence, it is important to manage TAN levels below 1 mg L−1 in the culture system of E. suratensis to ensure good health. [ABSTRACT FROM AUTHOR]

Water quality early warning is a key aspect in industrial recirculating aquaculture systems for high-density shrimp farming. The concentrations of ammonia nitrogen and nitrite in the water significantly impact the cultured animals and are challenging to measure in real-time, posing a substantial challenge to water quality early warning technology. This study aims to collect data samples using low-cost water quality sensors during the industrial recirculating aquaculture process and to construct predictive values for ammonia nitrogen and nitrite, which are difficult to obtain through sensors in the aquaculture environment, using data prediction techniques. This study employs various machine learning algorithms, including General Regression Neural Network (GRNN), Deep Belief Network (DBN), Long Short-Term Memory (LSTM), and Support Vector Machine (SVM), to build predictive models for ammonia nitrogen and nitrite. The accuracy of the models is determined by comparing the predicted values with the actual values, and the performance of the models is evaluated using Mean Absolute Error (MAE), Mean Absolute Percentage Error (MAPE), and Root Mean Square Error (RMSE) metrics. Ultimately, the optimized GRNN-based predictive model for ammonia nitrogen concentration (MAE = 0.5915, MAPE = 28.95%, RMSE = 0.7765) and the nitrite concentration predictive model (MAE = 0.1191, MAPE = 29.65%, RMSE = 0.1904) were selected. The models can be integrated into an Internet of Things system to analyze the changes in ammonia nitrogen and nitrite concentrations over time through aquaculture management and routine water quality conditions, thereby achieving the application of recirculating aquaculture system water environment early warning technology. [ABSTRACT FROM AUTHOR]

This study aims to analyze the addition of EM-4 probiotics with different concentrations to the cultivation media on the growth and survival of freshwater pomfret fish (C. macropomum). This research was carried out for 50 days at the Fish Production and Reproduction Laboratory, Aquaculture Study Program, Faculty of Agriculture, Mataram University. The method used was an experiment using a Completely Randomized Design (CRD) consisting of 4 treatments and three replications, namely without the addition of probiotics or control (P1); probiotic EM-4 0.5 ml/L (P2); probiotic EM-4 1.5 ml/L (P3); and probiotic EM-4 2.5 ml/L (P4). Test parameters include absolute weight, absolute length, specific growth rate, survival rate, feed conversion ratio, feed utilization efficiency, air quality, and bacterial density. Data analysis used analysis of variance (ANOVA) at a confidence level of 95%. If the research results show significant differences, further tests use the Duncan Multiple Range Test (DMRT). The research showed that adding EM-4 probiotics to the rearing media at different concentrations could significantly affect (p<0.05) fish survival rate, absolute weight, specific growth rate, feed conversion value, and feed utilization efficiency. The treatment of adding EM-4 probiotics to the maintenance media with a concentration of 1.5 ml/L of air provides the best value for survival rates, growth, FCR, and EPP. It can maintain the quality of the cultivation media in good condition for the growth of freshwater pomfret (C. macropomum). [ABSTRACT FROM AUTHOR]

The available models that predict total ammonia nitrogen concentration ([TAN]) in anaerobic digestion (AD) overestimate or underestimate the inhibition effect of [TAN], making them impractical to be implemented in full-scale digesters. Therefore, this study was conducted to establish a general and simple model to predict [TAN] with a decent predictive power by implementing machine learning modeling approaches. The experiment was conducted on AD reactors treating fish waste with three different feeding strategies and digestion times. Of 324 data entries, 80% and 20% were used for model training and testing. Cross-validation was also performed to determine the flexibility level and estimate the accuracy of the test dataset. Nine individual models were trained independently on training dataset, and the best-tuned models were inputted into voting regressor (VR) algorithm. VR outperformed other trained models with RMSEtest = 0.15, R2test = 0.98, and 4.76% of model error. The model's generality was also confirmed by high coefficient of variation of several features used for model establishment, representing the complexity of AD process. Therefore, this model can be implemented to predict [TAN] in other AD systems, especially in systems treating high protein contents. It will be beneficial to maintain stability and improve the efficiency of AD. [ABSTRACT FROM AUTHOR]

A field study evaluated the safe loading density for live transportation of rainbow trout, Oncorhynchus mykiss (Walbaum, 1792), yearlings in plastic bags of super-oxygenated water. The experimental fish (197.5 ± 40 g) were starved for 72 h and mildly sedated with clove oil (40 µL.L-1 for 2–3 min) before packing. Three loading densities of live rainbow trout (120, 170, 230 g.L-1) were packed in plastic bags containing 6 L of stream water and 10–12 L of medical-grade oxygen gas. Six replicate bags per loading density were then subjected to 10 h of transportation by road at ~10 °C. On arrival at the destination, important water quality indicators and fish survival were recorded from each plastic bag. With increasing fish loading density, there was a corresponding increase in the concentrations of carbon dioxide (CO2), total ammonia nitrogen (TAN), free ammonia (NH3), total dissolved solids (TDS) concentrations and specific conductivity in the transport water, and a decrease in dissolved oxygen (DO, R² = 0.91-0.99). These differences in vital water quality indicators were significantly more in the 230 g.L-1 group. However, there was no mortality even at the highest loading density, as the critical water quality parameters did not cross the acute lethal thresholds for rainbow trout. Based on the findings, it is recommended that a loading density of 230 g.L-1 is safe for live transportation of rainbow trout yearlings in plastic bags over a transport duration of 10 h at ~10 °C, following adequate starvation and mild sedation. [ABSTRACT FROM AUTHOR]

Quick-start nitrifying products (QSNP) are sold to aquarium hobbyists with the claim that the nitrogen cycle is rapidly initiated allowing for instant addition of fish. Despite these claims, none of these products have been the subject of peer-reviewed evaluation. Six 10-gallon aquaria were used to simulate a naïve fresh water system. Water temperature, pH and dissolved oxygen were measured to ensure stability between aquaria. On Day 0, 1.0-ppm ammonium hydroxide was added to each of the aquaria. Five aquaria received a different QSNP on Day 1 of the study. One aquarium acted as a control, receiving no QSNP. Total ammonia nitrogen (TAN), nitrite and nitrate levels were monitored every 48-hours for 14 days. Total ammonia nitrogen concentrations were significantly lower in the Tetra samples compared to all other samples and controls (all P < 0.001). Additionally, TAN concentrations were significantly lower on days 4 to 14 compared to baseline (all P < 0.001). There were no significant differences in nitrite concentrations by treatment (F = 1.3, P = 0.263) or time (F = 1.0, P = 0.416). Nitrate concentrations were significantly higher in the Cycle (P < 0.001) and Tetra (P = 0.001) samples compared to the control samples. Nitrate concentrations were also found to be significantly higher on days 4 (P = 0.027), 10 (P = 0.041), 12 (P = 0.011), and 14 (P = 0.007) compared to baseline. Four out of 5 QSNP failed to reduce TAN concentrations from baseline levels over the 14-day test period. One of the QSNP appears to significantly be able to reduce TAN concentrations in controlled freshwater aquaria. Quick-start nitrifying products should not be recommended as a sole method when initiating the nitrogen cycle in fresh water aquaria until further studies have evaluated these products. [ABSTRACT FROM AUTHOR]

Population declines in freshwater mussels (Unionida) resulting from failed recruitment, together with episodic water pollution potentially leading to juvenile mussel mortality, are often suspected (but rarely well documented), even in the most strictly protected aquatic areas.The aim of this study was to test a robust design for an in situ investigation of the water pollution effects on juvenile freshwater pearl mussel (FPM, Margaritifera margaritifera) in the protected Malše River (Czech Republic), which acts as a model system. A 30‐km river reach was delineated to include a section with previously recorded episodic multiple point‐source pollution events, as well as downstream and upstream control sections. Juvenile FPMs in open water mesh cages were exposed to river water at 15 sites in 42 exposure units (342 juveniles in individual chambers), and their survival and shell growth were assessed after a 33‐day period of low‐flow and high‐temperature conditions. The main physicochemical indicators related to municipal water pollution were measured weekly.The study results confirmed significantly impaired water quality indicated by episodic changes in total ammonia nitrogen (up to 1.037 mg L−1), total phosphorus (up to 0.516 mg L−1) and oxygen saturation (down to 75.0%) in the impaired section. While the growth of FPM (corrected for temperature effects) was significantly increased (shell length increment: 32.7 ± 9.7% – impaired, 26.4 ± 10.0% – control sections; mean ± SD), the survival (mean ± SD) of juveniles was significantly decreased in the impaired section (86.4 ± 12.5%) compared with the control sections (97.4 ± 5.7%).This study has demonstrated the capacity of applying a caged bivalve model at a fine spatial scale within a longitudinal river profile to document the impacts of water pollution. The methodology applied here may provide a useful tool for assessing and improving the level of water quality management and is applicable in FPM action plans and stream biotope conservation in general. [ABSTRACT FROM AUTHOR]

Gas-permeable membrane (GPM) technology is a novel alternative to reduce N content in wastewater while recovering N in the form of an ammonium salt solution that can be used as fertilizer. This work aims to elucidate the effects of three operational conditions on the performance of GPM technology for ammonia recovery in batch conditions using synthetic wastewater that simulates livestock wastewater. Firstly, the effect of the ratio of the initial mass of total ammonia nitrogen (TAN) per membrane surface from 197 to 936 g N per m2 of membrane was investigated. The highest ratio presented the highest TAN recovery rate (90 g N m−2 d−1). Secondly, the influence of the ratio of the volume of wastewater per volume of acidic trapping solution in the range from 7.8 to 33.3 L L−1 was studied. In this case, the higher the ratio, the higher the N concentration in the trapping solution, achieving a N concentration of 43,773 mg N L−1 with a ratio of 33.3 L L−1. Finally, two different TAN concentrations (<0.1 and 30 g N L−1) in the acidic trapping solution were evaluated. The use of a trapping solution with a TAN concentration of 30 g N L−1 led to a reduction in the TAN recovery rate, which meant that the diffusion of ammonia through the membrane was more difficult as the trapping solution became saturated with TAN. Overall, the tested conditions highly influence the performance of GPM technology, and therefore, these conditions should be set to optimize the ammonia recovery and reduce nitrogen losses. [ABSTRACT FROM AUTHOR]

This study evaluated the effects of the probiotic Bacillus spp. isolated from African nightcrawler (Eudrilus eugeniae) on the growth and survival performances of Nile tilapia (Oreochromis niloticus). A total of 400 Nile tilapia fingerlings (1.76 ± 0.07 g) were equally and randomly distributed into 20 glass aquaria and divided into five experimental groups with four replicates. Each experimental group was fed with a commercial diet (control) supplemented (at 108 CFU·g−1) with one of the four Bacillus spp. (ANSCI9, BFAR9, RM3, and RM10) at five percent of their body weight. After 30 days of feeding, the surviving fish were challenged with Aeromonas hydrophila to observe their survival. The treatment groups supplemented with BFAR9 (2.73 ± 0.26 g) and RM10 (3.15 ± 0.30 g) showed significantly higher (P < 0.05) absolute growth than the control (2.20 ± 0.16 g) group. Furthermore, those given with RM10 had better (P < 0.05) specific growth rate (SGR) (1.60 ± 0.10%·day−1) relative growth rate (RGR) (181.39 ± 18.16%) and feed conversion ratio (FCR) (1.99 ± 0.13) compared to the control group (SGR = 1.29 ± 0.07%·day−1; RGR = 129.84 ± 9.77%; FCR = 2.60 ± 0.16). The challenge test revealed that all Bacillus spp.-treated groups showed significantly higher (P < 0.05) survival rates (ANSCI9 = 82.5 ± 8.16%; BFAR9 = 80.0 ± 10.00%; RM3 = 77.5 ± 20.82%; RM10 = 85.0 ± 10.00%) than the control group (55.00 ± 19.15%), with the highest relative level of protection recorded for RM10 (66.67%). These results revealed that the probiotic Bacillus spp. isolated from E. eugeniae improved the growth, feed utilization, waste excretion, and the disease resistance of Nile tilapia. [ABSTRACT FROM AUTHOR]

High solids anaerobic digestion (HS‐AD) is an attractive energy‐producing technology; however, high total solids (TS) content may inhibit methanogens due to high volatile fatty acid (VFA) and total ammonia nitrogen concentrations. The objective of this paper is to quantify rate‐limiting metabolic kinetic parameters to determine the influence of TS content during anaerobic digestion of fecal sludge. Two TS content: 11% and 17% microcosms were analyzed. Good performance was observed in both systems, with volatile solid (VS) removal greater than 50%, CH4 yield between 0.44 and 0.56 m3 CH4/g VS added and cumulative CH4 production between 1.78 and 2.03 m3 CH4/m3 digester‐day. At 11% TS VFA consumption and VS removal had a positive correlation to CH4 production while the 17% TS microcosm had a negative correlation with both. This is the first study to determine the kinetic parameters for hydrolysis, VFA consumption, and methanogenesis during digestion of fecal sludge. These kinetic parameters are necessary in the design and operation of anaerobic digestion systems treating fecal sludge. [ABSTRACT FROM AUTHOR]

ABSTRACT This study aimed to assess the anaerobic digestion response of laying hen manure with different inclusion levels of biochar in batch reactors as measured by physicochemical parameters, biogas production and digestate quality. Four levels of biochar inclusions (0, 2.5, 5.0 and 7.5%) were tested with 3 replicates each. Twelve two-liter anaerobic batch reactors were used for 86 days at 35°C. Substrate and digestate of each treatment were assessed for monitored parameters, biogas production and digestate quality. Increased levels (0, 2.5, 5.0 and 7.5%) of biochar were found to gradually reduce total ammonia nitrogen (1794.33, 140.84, 950.81 and 509.32 mg.L-1, respectively). Despite the positive effect of biochar to accelerate initial biogas production, its use at any inclusion rate did not contribute significantly to biogas production in terms of biogas yield or digestate quality as compared to control treatment.

Copyright of South China Fisheries Science is the property of South China Fisheries Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The 'Zebra 2' strain of the Manila clam (Ruditapes philippinarum) is a newly bred for aquaculture in the low temperature Bohai and Yellow seas in northern China. The goal of this study was to determine the tolerance of 'Zebra 2' clams at early developmental stages to total ammonia nitrogen (TAN) under acute stress and continuous subacute stress levels. 'Zebra 2' were cultured under TAN stress at water salinity of 27–28, temperature of 21–28°C and pH of 8.0–8.2. Survival rate and production of clams from the fertilized egg to juvenile stages were measured. The acute stress test revealed that the median effective concentrations of TAN for hatchability and deformity of fertilized eggs at 24 h were 7.08 and 15.12 mg/L, with the unionized ammonia (UIA) at 0.22 and 0.36 mg/L respectively. The 50% lethal concentrations for D‐shaped larvae (shell length 101.50 μm), umbo larvae (179.67 μm) and juveniles (610.50 μm) at 96 h were 3.28, 48.90 and 57.57 mg/L, with UIA at 0.10, 2.08 and 2.99 mg/L respectively. These results suggested that the 'Zebra 2' clams hatching and D‐shaped larvae stages were most sensitive to TAN and that the tolerance significantly increased after the umbo larval stage. In the continuous subacute stress test, 'Zebra 2' juveniles were observed under all the treatments after 53 days of exposure to TAN stress at 5.45 mg/L (0.23 mg/L UIA). The maximal acceptable toxicant concentration of UIA used to determine the mortality rate, yield and relative yield was ranged from 0.12 to 0.23 mg/L. These findings suggested that maintaining TAN <0.22 mg/L and UIA ≤0.021 mg/L at seawater pH ≤8.5, salinity ≥25 and water temperature ≤25°C would improve larval rearing of 'Zebra 2' clams. [ABSTRACT FROM AUTHOR]

Current Chinese surface water environmental quality standard GB3838-2002 for ammonia fails to take water quality factors and native organism distributions in different basins into consideration. In this study, ammonia toxicity tests were performed using three aquatic organisms native to the Shaying River Basin (China). Published ammonia toxicity data with pH and temperature, and toxicity data acquired in this study were used to establish water quality criteria. The final criterion maximum concentration (CMC) and criterion continuous concentration (CCC) for the Shaying River Basin were 5.09 and 1.36 (mg total ammonia nitrogen (TAN))/L (pH 7 and 20 °C), respectively. In addition, based on the corresponding relationship between ammonia toxicity and temperature and pH, the ecological risk assessment of ammonia was conducted in different seasons for the Shaying River using a tiered approach of both hazard quotient (HQ) and the joint probability (JPC) methods. Two methods gave consistent results: the ecological risks of ammonia to aquatic species in the Shaying River Basin were severe and the risk could be ranked as wet season > flat season > dry season. It is therefore indicating that monitoring, evaluation, and early warning of ammonia pollution need to be taken to prevent and control the risks posed by ammonia pollution, especially for wet season (because of high temperatures and pH) or flat season (because of high pH values). We hope the present work could provide valuable information to manage and control ammonia pollution in the Shaying River Basin.

This work presents a portable microfluidic paper-based analytical device (micro-PAD) card for the quantification of total ammonia nitrogen in human saliva. The amount of total ammonia nitrogen in saliva can be an indicator of the status of the oral microbiome with potential correlation to kidney health problems. The developed micro-PAD card comprises twenty units consisting of three stacked layers of circular discs: the sample layer, paper discs impregnated with sodium hydroxide solution, the PTFE membrane layer, and the detection layer, paper discs impregnated with bromothymol blue. The twenty units were aligned on transparent laminating pouches laminated to form the micro-PAD card (7.5 cm × 10.5 cm). Saliva samples can be directly dispensed onto the micro-PAD card and the detection was achieved by the BTB indicator color change, from yellow to blue, after conversion of ammonium into ammonia and diffusion of the ammonia gas through a hydrophobic layer. The determination of total ammonia nitrogen in saliva using the developed micro-PAD card intended to be very simple method and operated without the need of laboratory equipment. A quantification limit of 11.3 NH4+mg L-1 and linear application range from up to 150 NH4+mg L-1 were obtained making it suitable for the expected concentrations of total ammonia nitrogen in human saliva. It was successfully applied to saliva samples and its validation obtained by comparison against a potentiometric method. The card is stable for at least 1 month making it ideal as a portable device for point-of-care diagnosis. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Hydrobiology / Shuisheng Shengwu Xuebao is the property of Editorial Department of Journal of Hydrobiology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Daily water exchange rate was over 50% in the traditional intensive culture for Anguilla marmorata, which resulted in a huge waste of fresh water resources and the pollution of surrounding water. To save water and reduce pollution, the comparison experiment on biofilm–biofloc technique applied in Anguilla marmorata intensive culture was implemented. Nine tanks were randomly divided into three groups. Biofilm water-cleaning grille was set up at 7.1% of water volume, and supplementary sucrose was added to water at 75% of feed per day in treatment group I; biofilm water-cleaning grille was set up at 7.1% of water volume, and supplementary starch was added to water at 75% of feed per day in treatment group II; the other group III without any treatment as the control group. The results showed that the daily water exchange rate of treatment group I and treatment group II were significantly lower than the control by 69.2% and 74.4%, respectively (p < 0.05). The concentrations of total ammonia nitrogen, nitrite nitrogen, nitrate nitrogen, total nitrogen, total phosphorus, solved reactive phosphorus (SRP) and Vibrio density in treatment group I were lower than the control by 43.5%, 38.3%, 32.4%, 22.4%, 35.8%, 32.9%, and 45%, respectively (p < 0.05). While, the concentrations of the same mentioned parameters except SRP in treatment group II were lower than the control by 27.2%, 51.7%, 37.8%, 33.3%, 20.4%, and 50%, respectively (p < 0.05). The growth rate of treatment group I and treatment group II were significantly higher than the control by 37.8% and 14.9%, respectively (p < 0.05). Therefore, biofilm–biofloc technique had remarkable water-saving and pollution-reducing effect and should be extensively used in aquaculture. [ABSTRACT FROM AUTHOR]

An aquaculture system can be a potentially significant source of antibacterial compounds and ammonia in an aquatic environment. In this study, the removal of total ammonia nitrogen and florfenicol antibiotic from synthetic aqueous wastewater was assessed by applying a commercial TFC (thin film composite) polyamide nanofilter. The effects of pH (6.5-8.5), pressure (4-10 bar), concentration of total ammonia nitrogen (1-9 mg/L), and florfenicol (0.2-5 mg/L) on the removal efficiency of the nanofilter were studied at a constant 70% recovery rate. It was found that by increasing the pH within the range of 6.5 to 8.5, it enhanced the removal efficiency by up to 98% and 100% for total ammonia nitrogen and florfenicol, respectively. With an increase in pressure from 4 to 7 bar, the removal percentage increased and then, it decreased from 7 to 10 bar. The interactions factors did not have significant effects on the both pollutants removal efficiencies. To obtain optimal removal efficiencies, an experimental design and statistical analysis via the response surface method were adopted.

The present study aimed at determining the effects of the interaction between afternoon aeration and stocking density of Nile tilapia on variables of water and soil quality, growth performance and effluent quality. The experiment was a 3 x 2 factorial randomized block design, with three stocking densities (8, 12 and 16 fish per tank or 43.5, 65.3, and 87.0 g m-3) under two mechanical aeration regimes, absence (control; three replicates) and afternoon aeration (four replicates). The afternoon aeration was carried out from 12.00 a.m. up to 18.00 p.m. from the 3rd week until the end of the experiment. Except for the 16-fish tanks, the lowest concentrations of total ammonia nitrogen were found in the tanks with higher density of fish provided with afternoon aeration. Nitrite concentrations were lower in the 8-fish aerated tanks. In intensive system, the afternoon aeration of the fish culture water is an efficient management of water quality to remove gaseous ammonia and nitrite from water, but it is not appropriate to remove hydrogen sulfide from water.

This study investigated the effect of five different concentrations of total ammonia nitrogen (TAN)and free ammonia (FA) on the methane yield and digester performance under thermophilic conditions(50°C). Five identical continuously fed digesters were used. The experiment was run for four timeshydraulic retention time (HRT). Data were statitically analysed using the data Analysis Tool Packavailable with the Microsoft Excel program. Different ammonia levels were obtained by pulsing urea toobtain the target level of TAN and FA, and to subsequently maintaining the concentration of ammonialevels by daily urea additions. The result showed a strong negative correlation between both TAN andFA concentrations and methane yield. The methane yield was reduced by 24, 30, 52 and 66% indigesters that had TAN levels of 2.9, 3.6, 4.4 and 5.1 g/L, respectively, corresponding to 0.7, 1.1,1.5 and1.8 g/L FA. Total volatile fatty acid and especially isovaleric and isobutyric acid concentrations wereelevated during ammonia inhibition. Concentration of TAN in the biogas digester exceeding 3 g/Lindicating that very often the full biogas potential is not achieved due to ammonia inhibition and thatlonger HRT should be used to compensate or a lower process temperature should be chosen.

Graphical abstract Highlights • Acclimation increased the tolerance to ammonia inhibition over the acclimated range. • Total ammonia rather than free ammonia would be the direct inhibition criterion. • Propionate degradation was more sensitive to NH 3 than acetoclastic methanogenesis. Abstract This work evaluated the toxicity of ammonia toward mesophilic methanogenic microflora, with respect to the acclimation and pH. Microflora acclimated to total ammonia nitrogen (TAN) concentrations of 1.0–2.5 g N/L and neutral to alkaline pH, 7.5–8.0, were used for anaerobic toxicity assays (ATA) with TAN up to 6.1 and pH ranged from 7 to 8.2. The effect of ammonia on the specific methanogenic activity (SMA) and methane yield (MY) was described using a noncompetitive model. Acclimation increased the tolerance of the methanogenic microflora to ammonia over the acclimation range. There was no significant difference in the values of SMA and MY at each TAN concentration in the examined pH range, although free ammonia nitrogen (FAN) concentrations increased along with pH. It implied that TAN rather than FAN would be the useful criterion for ammonia inhibition. Propionate degradation was more inhibited compared to acetoclastic methanogenesis by ammonia. The half-maximal inhibitory concentrations (IC 50) of TAN for the SMA from acetate, SMA from propionate, MY from acetate, and MY from propionate were 3.42–4.26, 3.14–3.91, 3.67–4.07, and 3.34–3.88 g N/L, respectively, at pH 7.4. 454-pyrosequencing analysis of the inoculum showed that the archaeal community was dominant of Methanosarcinaceae and Methanobacteriaceae , which were known as tolerant to ammonia inhibition. [ABSTRACT FROM AUTHOR]

Ammonia is deemed one of the most important pollutants in the freshwater environment because of its highly toxic nature and ubiquity in surface water. This study thus aims to derive the criteria for ammonia in freshwater to protect aquatic life because there are no water quality criteria for ammonia in Korea. Short-term lethal tests were conducted to perform the species sensitivity distribution (SSD) method. This method is widely used in ecological risk assessment to determine the chemical concentrations to protect aquatic species. Based on the species sensitivity distribution method using Korean indigenous aquatic biota, the hazardous concentration for 5% of biological species (HC 5 ) value calculated in this study was 44 mg/L as total ammonia nitrogen (TAN). The value of the assessment factor was set at 2. Consequently, the criteria for ammonia were derived as 22 mg/L at pH 7 and 20 °C. When the derived value was applied to the monitoring data nationwide, 0.51%, 0.09%, 0.18%, 0.20%, and 0.35% of the monitoring sites in Han River, Nakdong River, Geum River, Youngsan River, and lakes throughout the nation, respectively, exceeded this criteria. The Ministry of Environment in Korea has been considering introducing water quality standard of ammonia for protecting aquatic life. Therefore, our results can provide the basis for introducing the ammonia standard in Korea. [ABSTRACT FROM AUTHOR]

In recent years, (bio)electrochemical systems (B)ES have emerged as an energy efficient alternative for the recovery of TAN (total ammonia nitrogen, including ammonia and ammonium) from wastewater. In these systems, TAN is removed or concentrated from the wastewater under the influence of an electrical current and transported to the cathode. Subsequently, it can be removed or recovered through stripping, chemisorption, or forward osmosis. A crucial parameter that determines the energy required to recover TAN is the load ratio: the ratio between TAN loading and applied current. For electrochemical TAN recovery, an energy input is required, while in bioelectrochemical recovery, electric energy can be recovered together with TAN. Bioelectrochemical recovery relies on the microbial oxidation of COD for the production of electrons, which drives TAN transport. Here, the state-of-the-art of (bio)electrochemical TAN recovery is described, the performance of (B)ES for TAN recovery is analyzed, the potential of different wastewaters for BES-based TAN recovery is evaluated, the microorganisms found on bioanodes that treat wastewater high in TAN are reported, and the toxic effect of the typical conditions in such systems (e.g., high pH, TAN, and salt concentrations) are described. For future application, toxicity effects for electrochemically active bacteria need better understanding, and the technologies need to be demonstrated on larger scale. [ABSTRACT FROM AUTHOR]

Semi-intensive Indian Major Carp (IMC) culture was practised in polythene lined dugout ponds at the Aquacultural Farm of Indian Institute of Technology, Kharagpur, West Bengal for 3 consecutive years at three different stocking densities (S.D), viz., 20,000, 35,000 and 50,000 numbers of fingerlings per hectare of water spread area. Fingerlings of Catla, Rohu and Mrigal were raised at a stocking ratio of 4:3:3. Total ammonia nitrogen (TAN) value along with other fishpond water quality parameters was monitored at 1 day intervals to ensure a good water ecosystem for a better fish growth. Water exchange was carried out before the TAN reached the critical limit. Field data on TAN obtained from the cultured fishponds stocked with three different stocking densities were used to study the dynamics of TAN. A developed model used to study the nutrient dynamics in shrimp pond was used to validate the observed data in the IMC pond ecosystem. Two years of observed TAN data were used to calibrate the spreadsheet model and the same model was validated using the third year observed data. The manual calibration based on the trial and error process of parameters adjustments was used and several simulations were performed by changing the model parameters. After adjustment of each parameter, the simulated and measured values of the water quality parameters were compared to judge the improvement in the model prediction. Forward finite difference discretization method was used in a MS-Excel spreadsheet to calibrate and validate the model for obtaining the TAN levels during the culture period. Observed data from the cultured fishponds of three different S.D were used to standardize 13 model parameters. The efficiency of the developed spreadsheet model was found to be more than 90% for the TAN estimation in the IMC cultured fishponds. [ABSTRACT FROM AUTHOR]

Ammonia toxicity was investigated in mesophilic (37 °C) and thermophilic (55 °C) digesters using high and low-nitrogen food wastes (FW). Mesophilic inoculum was successfully acclimated to thermophilic conditions by a step change in temperature followed by incremental increases in organic loading rate (OLR). Digestion performance and stability were monitored via volatile fatty acid (VFA) profiles, alkalinity, specific methane production (SMP) and volatile solids (VS) destruction. High-nitrogen mesophilic digesters stabilised by day 70 and responded well to increases in OLR, with a SMP of 0.45 L CH 4 g −1 VS, stable pH, and VFA <0.2 g L −1 . Thermophilic digesters fed on high and low-nitrogen FWs showed almost identical responses to acclimatisation. Behaviour then deviated, with high-nitrogen digesters accumulating VFA. Stable pH could be maintained for up to 310 days before eventual failure at total ammonia nitrogen (TAN) concentration >5.0 g N L −1 , although accumulation of propionic and other longer-chain VFA began at TAN ∼3.5 g N L −1 . The low-nitrogen digesters showed no VFA accumulation, and had a SMP of ∼0.39 L CH 4 g VS L −1 day −1 with 91% VS destruction. After 384 days the TAN concentration was increased from ∼0.7 g N L −1 by urea addition. This resulted in progressive VFA accumulation in one digester when TAN reached ∼3.5 g N L −1 , while stable operation at very low VFA was possible at up to ∼2.5 g N L −1 in the second digester. The results confirmed acclimatisation to thermophilic conditions was possible on a far shorter timescale than to high TAN concentrations. [ABSTRACT FROM AUTHOR]

High concentration of total ammonia nitrogen (TAN) in the form of urea is known to inhibit the performance of many biological wastewater treatment processes. Microbial fuel cells (MFCs) have great potential for TAN removal due to its unique oxic/anoxic environment. In this study, we demonstrated that increased urea (TAN) concentration up to 3940 mg/L did not inhibit power output of single-chambered MFCs, but enhanced power generation by 67% and improved coulombic efficiency by 78% compared to those obtained at 80 mg/L of TAN. Over 80% of nitrogen removal was achieved at TAN concentration of 2630 mg/L. The increased nitrogen removal coupled with significantly enhanced coulombic efficiency, which was observed for the first time, indicates the possibility of a new electricity generation mechanism in MFCs: direct oxidation of ammonia for power generation. This study also demonstrates the great potential of using one MFC reactor to achieve simultaneous electricity generation and urea removal from wastewater. [ABSTRACT FROM AUTHOR]

This study aimed at providing a better understanding of the influence of support media (10 g/L of zeolites, 10 g/L of activated carbons, and 1 g/L of chitosan) on key phylotypes steering anaerobic digestion (AD) performance in presence of 19 g/L of Total Ammonia Nitrogen (TAN) within batch digesters. Support media did not influence TAN concentration. However, both zeolites and activated carbon 1 reduced methanization lag phase by 47% and 25%, respectively. By contrast, activated carbon 2 and chitosan led to an increase of methanization lag phase by 51% and 32%, respectively. 16S rRNA gene sequencing revealed that zeolites preserved Methanosarcina and enhanced Methanobacterium. In presence of activated carbon 1, Methanoculleus , became predominant earlier than without support while chitosan and activated carbon 2 limited its implantation. This study highlighted potentialities to use supports to enhance AD stability under extreme TAN concentration and evidenced their specific influence on the microbiota composition. [ABSTRACT FROM AUTHOR]

A ratio control strategy was implemented in a continuous moving bed biofilm reactor (MBBR) to investigate the response to different temperatures. The control strategy was designed to maintain a constant ratio between dissolved oxygen (DO) and total ammonia nitrogen (TAN) concentrations. The results revealed that a stable nitritation in a biofilm reactor could be achieved via ratio control, which compensated the negative influence of low temperatures by stronger oxygen-limiting conditions. Even with a temperature as low as 6 °C, stable nitritation could be achieved when the controlling ratio did not exceed 0.17. Oxygen-limiting conditions in the biofilm reactor were determined by the DO/TAN concentrations ratio, instead of the mere DO concentration. This ratio control strategy allowed the achievement of stable nitritation without complete wash-out of NOB from the reactor. Through the ratio control strategy full nitritation of sidestream wastewater was allowed; however, for mainstream wastewater, only partial nitritation was recommended. [ABSTRACT FROM AUTHOR]

Copyright of Tecnología y Ciencias del Agua is the property of Instituto Mexicano de Tecnologia del Agua (IMTA) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this study, we evaluated ammonia toxicity in mesophilic anaerobic digestion at various pH values and total ammonia nitrogen (TAN) concentrations. We performed anaerobic toxicity assays (ATAs) to evaluate the toxicity effects of TAN and pH on mesophilic anaerobic digestion. Modeling based on the results of the ATAs indicated that the specific methanogenic activity (SMA) decreased by 30% at a TAN concentration higher than 3.0 g/L compared to a TAN concentration of 0 g/L. In addition, the highest SMA for a given TAN level (0.5-10.0 g/L) was observed at a pH of around 7.6. The results of bacterial community analyses showed that the diversity and richness of microorganisms with increasing TAN concentration were decreased. Chloroflexi and Synergistetes were the dominant phyla at TAN concentrations less than 3.0 g/L, and Firmicutes was the dominant phylum at TAN concentrations higher than 3.0 g/L, implying that the ammonia toxicity concentration may influence the kind of dominant species. In conclusion, to start a stable mesophilic anaerobic digestion concerning ammonia toxicity, a TAN concentration less than 3.0 g/L is preferable. [ABSTRACT FROM AUTHOR]

Organic carbon source and C/N ratio play an important role in aquaculture system with biofloc technology application. Nitrogen control by adding carbohydrates to the water to stimulate heterotrophic bacterial growth by converting nitrogen into bacterial biomass. The study investigated the effect molasses, tapioca, tapioca by product and rice bran as carbon sources in a biofloc media at three different C/N ratios i.e. 10, 15, and 20 on total ammonia reduction in biofloc media. Five liters of biofloc media in a conical tank was prepared for each replicate, which consisted of 500 mL of biofloc suspension collected from a shrimp culture unit with biofloc technology application and 4.5 L seawater. Pacific white shrimp culture was performed in 40L glass aquaria at a shrimp density of 30/aquarium. There was a significant interaction between carbon source and the C/N ratio applied (P<0.05). The use of molasses resulted in the highest reduction rate irrespective to the C/N ratio. [ABSTRACT FROM AUTHOR]

Copyright of Acta Scientiarum: Animal Sciences is the property of Universidade Estadual de Maringa and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

L'azote ammoniacal est un toxique potentiel en élevage de poissons ayant des effets plus ou moins sévères selon la concentration ambiante et la durée d'exposition. Dans une première partie, nous rappelons que l'AAT (somme de NH4+ et NH3) est toxique essentiellement sous sa forme NH3 . Dès qu'un poisson se trouve en présence de niveaux d'AAT anormalement élevés, il y a entrée d'AAT surtout sous forme de NH3 et diffusion dans les différents compartiments du poisson (à l'équilibre, le NH4+ est dominant). Selon les conditions d'exposition, différents états d'équilibre se succèdent entre le poisson et le milieu dès lors que ses capacités d'excrétion sont affectées. A partir d'un certain niveau de concentration d'AAT dans le sang et les tissus, le poisson n'arrive plus à réguler ses fonctions vitales, le seuil de toxicité est atteint. Nous faisons ensuite la synthèse de l'état des connaissances des effets de l'AAT sur la survie et la croissance du turbot (Psetta maxima) en le comparant à d'autres espèces de poissons élevées en mer ou en eau douce. A court terme, la sensibilité du turbot à l'AAT est du même ordre de grandeur que celle de la daurade et du bar, la 96-h CL50 (concentration létale pour 50 % de la population) varie dans une fourchette de 1 à 3 mg/l NH3 . Des valeurs aussi élevées ne peuvent être qu'accidentellement rencontrées, même dans les élevages à haute densité. Chez toutes les espèces marines éprouvées, le seuil de toxicité chronique est plus bas, 0,8-1 mg/l NH3 pour une durée d'exposition n'excédant pas un mois. Chez le turbot, la croissance est ralentie à 0,33 mg/l NH3 en moyenne et sensiblement aux mêmes valeurs chez le bar et la daurade. Chez ces mêmes espèces selon la duré d'exposition, il y a risque de perturbation de la croissance au-dessus de 0,11 mg/l NH3 , ce qui correspond aux pics de concentrations dans les élevages à haute densité utilisant des circuits fermés. Ces seuils de sécurité en termes de croissance sont sensiblement plus bas chez les salmonidés (0,02-0,15 mg/l NH3), surtout pendant la phase d'eau douce. En définitive, dans des conditions de croissance par ailleurs optimales (facteurs du milieu et alimentation) le turbot et les poissons marins, pris au stade juvénile, sont relativement tolérants à l'AAT. Toutefois leur sensibilité est étroitement dépendante de facteurs environnementaux tels que le pH et la disponibilité en oxygène. Elle peut de même être modulée par les conditions d'exposition : pré-acclimatation, niveaux fluctuants d'AAT et durée d'exposition.

In this research, we identified genes associated with ammonia nitrogen (TAN) stress response and resistance in juveniles of the Zebra II strain and a wild population of the Manila clam Ruditapes philippinarum. Both groups were subjected to a 96 h acute toxicity test using TAN concentrations of 17.617 ± 0.634 and 16.670 ± 0.7 mg/l, respectively. We then collected samples, conducted transcriptome sequencing and screened the sequences for differentially expressed genes (DEGs) related to TAN stress response. We identified 2908 and 2861 DEGs in the Zebra II and wild clam groups, respectively, and the two groups had 626 DEGs in common. The verified DEGs had less of a detoxification effect in the wild population than that in the Zebra II group. Gene Ontology database analysis showed that Zebra II juveniles were mainly enriched in protein phosphorylation, purine nucleoside binding, and kinase activity, whereas the wild population juveniles were primarily enriched in oxidases activity, organic acid metabolic processes, and extracellular regions. Kyoto Encyclopedia of Genes and Genomes pathway analysis mainly highlighted aminoacyl tRNA biosynthesis in Zebra II juveniles and sphingolipid metabolism, FOXO signaling, biosynthesis of aminoacyl tRNA, and other pathways in the wild population. These results show that the toxic effect of TAN on the Manila clam is related to a variety of pathways, which are mainly related to immune response, inflammatory response, metabolic pathways, and nerve conduction. This study provides basic data and theoretical reference for revealing the molecular regulation mechanism of the improved TAN tolerance of Zebra II strain as compared with the wild population of Ruditapes philippinarum. [Display omitted] • Provide the basis of Molecular identification the Manila clam under TAN stress • The verified DEGs had less of a detoxification effect in the wild population than in the Zebra II group. • Toxic effects of ammonia nitrogen on Manila clam Ruditapes philippinarum are mainly related to immune response. [ABSTRACT FROM AUTHOR]